The physical nature of Lyα-emitting galaxies at z = 3.1

Eric Gawiser, Pieter G. Van Dokkum, Caryl Gronwall, Robin Ciardullo, Guillermo A. Blanc, Francisco J. Castander, John Feloneier, Harold Francke, Marijn Frank, Lutz Haberzettl, David Herrera, Thomas Hickey, Leopoldo Infante, Paulina Lira, José Maza, Ryan Quadri, Alexander Richardson, Kevin Schawinski, Mischa Schirmer, Edward N. TaylorEzequiel Treister, C. Megan Urry, Shanil N. Virani

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Abstract

We selected 40 candidate Lyα-emitting galaxies (LAEs) at z ≃ 3.1 with observed-frame equivalent widths greater than 150 Å and inferred emission-line fluxes above 2.5 × 10-17 ergs cm-2 s-1 from deep narrowband and broadband MUSYC images of the Extended Chandra Deep Field South. Covering 992 arcmin2, this is the largest "blank field" surveyed for LAEs at z ∼ 3, allowing an improved estimate of the space density of this population of (3 ±1) × 10-4 h703 Mpc-3. Spectroscopic follow-up of 23 candidates yielded 18 redshifts, all at z ≃ 3.1. Over 80% of the LAEs are dimmer in continuum magnitude than the typical Lyman break galaxy (LEG) spectroscopic limit of R = 25.5 (AB), with a median continuum magnitude R ≃ 27 and very blue continuum colors, V-z ≃ 0. Over 80% of the LAEs have the right UVR colors to be selected as LBGs, but only 10% also have R ≤ 25.5. Stacking the UBVRIzJK fluxes reveals that LAEs have stellar masses ≃5 × 108 h702 M⊙ and minimal dust extinction, AV ≲ 0.1. Inferred star formation rates are ≃6 h70-2 M⊙ yr-1, yielding a cosmic star formation rate density of 2 × 10-3 h70 M⊙ yr-1 Mpc-3. None of our LAE candidates show evidence for rest-frame emission-line equivalent widths EWrest > 240 Å that might imply a nonstandard initial mass function. One candidate is detected by Chandra, implying an AGN fraction of 2% ± 2% for LAE candidate samples. In summary, LAEs at z ∼ 3 have rapid star formation, low stellar mass, little dust obscuration, and no evidence for a substantial AGN component.

Original languageEnglish (US)
Pages (from-to)L13-L16
JournalAstrophysical Journal
Volume642
Issue number1 II
DOIs
StatePublished - May 1 2006

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Gawiser, E., Van Dokkum, P. G., Gronwall, C., Ciardullo, R., Blanc, G. A., Castander, F. J., Feloneier, J., Francke, H., Frank, M., Haberzettl, L., Herrera, D., Hickey, T., Infante, L., Lira, P., Maza, J., Quadri, R., Richardson, A., Schawinski, K., Schirmer, M., ... Virani, S. N. (2006). The physical nature of Lyα-emitting galaxies at z = 3.1. Astrophysical Journal, 642(1 II), L13-L16. https://doi.org/10.1086/504467